A330865 - OEIS

%I #11 Apr 28 2020 17:08:43

%S 7,9,8,6,9,6,3,1,5,9,5,6,4,6,3,0,8,4,8,6,3,8,0,6,7,0,4,2,2,1,0,9,6,1,

%T 3,8,6,9,1,4,9,2,8,7,4,1,8,5,1,2,9,1,2,3,4,8,3,7,2,6,6,4,0,6,4,5,9,0,

%U 2,4,3,1,1,2,9,6,8,6,5,4,3,0,6,7,6,6,4,1,0,6,5,9,8,7,3,9,6,2,3,2,2,2,5,7,1,0,1,5,8,5

%N Decimal expansion of cosh(Pi/2)/Pi.

%F Equals Sum_{k>=0} Pi^(2*k-1)/(4^k*(2*k)!).

%F Equals Product_{k>=2} (1 - (-1)^k/k^2).

%F Equals (i^(-i) + i^i)/(2*Pi), where i is the imaginary unit.

%e (1 - 1/2^2) * (1 + 1/3^2) * (1 - 1/4^2) * (1 + 1/5^2) * (1 - 1/6^2) * ... = (e^(Pi/2) + e^(-Pi/2))/(2*Pi) = 0.7986963159564630848638067...

%t RealDigits[Cosh[Pi/2]/Pi, 10, 110] [[1]]

%o (PARI) cosh(Pi/2)/Pi \\ _Michel Marcus_, Apr 28 2020

%Y Cf. A042972, A049006, A049541, A156648, A175615, A308715, A308716, A308718, A323982, A330864, A334402.

%K nonn,cons

%O 0,1

%A _Ilya Gutkovskiy_, Apr 28 2020